Single-chain polypeptides comprising troponin I and troponin C
This invention relates to single-chain polypeptides and their genetic sequences comprising human cardiac troponin I and troponin C. The single-chain polypeptide may be expressed recombinantly, and a linker peptide may be interposed between the troponin sequences. A linker peptide of about 6 to about 30 amino acids is preferred. The single-chain polypeptide has utility as a control or calibrator for troponin assays, for the purification of troponin subunits and as an antigen for the preparation of antibodies.
1. A single-chain polypeptide comprising a human cardiac troponin I, a peptide linker and a human cardiac troponin C.
2. The polypeptide of claim 1 having an amino acid sequence as set forth in (SEQ ID NO: 4).
3. The single-chain polypeptide of claim 1 wherein said troponin I has sequence SEQ ID NO:6.
4. A control or calibrator composition for a troponin I assay comprising the single-chain polypeptide of claim 1 .
5. A method for quantifying troponin I in a sample, the method comprising the following steps:
(1) detecting a known quantity of the single-chain polypeptide of claim 1 in a standard;
(2) detecting an unknown quantity of troponin I in a sample; and
(3) correlating the unknown quantity of troponin I in the sample with the known quantity of the single-chain polypeptide on the standard.